There are two issues involved, the impact on the residual vegetation and the damage to soil and water values. Damage is reduced by choosing the best method for the job and using well trained operators. Helicopter logging extraction usually causes the least damage and tracked or wheeled skidders the most.
Continuous cover forests on easy country generally require a denser roading network than forests which are clear felled. Ground harvest methods involve extracting logs by hauling through the trees to the road, either by small skidder, agricultural tractor, mini skidder or horse.
Roads must be built to a standard high enough to easily extract logs while protecting the soil from erosion. Unlike clear felling, where roads may only be heavily used once every 25 or 30 years, continuous cover forestry use will be lighter but more or less continuous.